Paid off Student Loan and FICO score decreased?

[CluelessCredit]

I'm about 7 years into a 10 year debt snowball on my student loan debt.  I recently finished paying off my higher interest rate (7%) 45k private student loan which leaves another 42k (6.3%) federal loan to go.

I log into Discover to check my FICO score which was previously 815, to find it sitting at 793.  The reasons given kinda left me dumbfounded:

Your FICO® Credit Score is affected by these key factors:

1. 1.PROPORTION OF LOAN BALANCES TO LOAN AMOUNTS IS TOO HIGH:

   When you first get a non-mortgage installment loan (like a car loan or student loan) your balance is generally high. As you pay down your loan, the balance decreases.

2.   2.LENGTH OF TIME REVOLVING ACCOUNTS HAVE BEEN ESTABLISHED:

      Longer credit histories indicate less risk to lenders. The age of your revolving accounts is relatively low.

The second reason has always been there as I had never touched a credit card until 2007.  I now have 3 CCs (cancelled Penfed gas card last year), the last of which was obtained in 2013.  But even so I still achieved a score of 815 with the short revolving credit history.

This doesn't really impact me in any real way.  I justrecently got a promotion, and I'm not looking to make any major purchases any time soon.  The only other change in my credit profile has been a soft pull initiated (auto approved automated phone menu) CLI to my Discover IT card.  I thought a paid off loan showed as something positive for 10 years or more?  Why would paying off a sizable student debt drop my score when it is only making my DTI ratio better? 

[user5387]

Installment loans tend to help your score.  I don't know if paying one off is the cause of the decrease, but there are various reports around here of people taking a hit in such a case.

There are other issues that can affect scores, for example a change in your utilization, or letting several CCs report a balance.

DTI is a big issue, but is not included in FICO scoring.

[CluelessCredit]

Thanks for the information. Guess I'll pull a credit report and see what it says. I'm just trying to understand this for when I finish paying off the next loan, at which point I will be looking into home ownership. Wouldn't want another unforeseen FICO drop when it matters most.

[Revelate]

As a heads up the Discover score is a Transunion one, and it is FICO '08 which isn't used on a mortgage.  Would recommend checking the Equifax Scorepower product before you head off into mortgageland, but sounds like you have a nice report anyway and shouldn't be a problem really.